1. Technical Field
The present invention relates to LED structures, and more particularly, to a high-power LED structure operable in a high-voltage environment.
2. Description of Related Art
U.S. Pat. No. 6,853,011 has disclosed a light emitting epi-layer structure containing a temporary substrate of absorption light type on one side while the other side thereof is then adhered to a transparent substrate of light absorption free by BCB bonding layer. After the temporary substrate is removed, the resulted light emitting structure is then patterned to form a connection channel to connect the first ohmic contact electrode and form an isolation trench to separate the active layer of the light emitting structure into two parts. Thereafter, a second ohmic contact electrode on the cladding layer and a bonding metal layer filled in the first channel and on second ohmic contact electrode are successively formed. The resulted LED structure is hence convenient for flip-chip structure since two bonding metal layers have the same altitude.
U.S. Pat. No. 6,998,642 has disclosed a semiconductor structure with two light emitting diodes in series connection. The semiconductor structure comprises two light emitting diodes (LEDs) having the same stack layers and abutting each other but spaced by an isolation trench. The stack layers from a bottom thereof include a thermal conductive substrate, a nonconductive protective layer, a metal adhering layer, a mirror protective layer, a p-type ohmic contact epi-layer, an upper cladding layer, an active layer, and a lower cladding layer. Two p-type ohmic contact metal electrodes for two LEDs are formed on an interface between the mirror protective layer and the ohmic contact epi-layer and buried in the mirror protective layer.
The stack layers have first trenches formed therein which expose the upper cladding layer and electrical connecting channels to connect p-type electrodes. The isolation trench is formed by patterning the exposed upper cladding layer until further exposing the nonconductive protective layer. Two n-type electrodes are formed on the lower cladding layer of two LEDs. A dielectric layer is deposited to fill the isolation trench and covered a sidewall of the first trench so that it can electrically isolate layers of the stack layers of the second LED while a metal connection trace formed thereon to connect the p-type ohmic contact electrode of the first LED and n-type of ohmic electrode of second LED.
Although the structure of U.S. Pat. No. 6,853,011 is applicable to flip-chip structures, it would be impossible to connect two of the LED structures without assistance of submounts. Besides, complexity of the flip-chip process could be significantly increased because there are numerous chips to be processed. On the other hand, while the structure of U.S. Pat. No. 6,998,642 enables the electrical connection between LEDs, metal-to-metal adherence where such electrical connection relies could be only achieved through a complex process, resulting in problems related to weak productivity and high manufacturing costs. Moreover, since the nonconductive layer is located at the boundary between the LEDs, the metal connection trace could only connect two electrically conducting plates and it would still be impossible to achieve a circuit layout with further complexity if no submounts are provided.
Thus, in view of the inconvenience and defects reflected in their configurations and applications, the existing LED structures need to be improved. Although all relevant manufactures have saved no efforts to solve the aforementioned problems, an applicable approach has not been developed. It is still a challenge for the manufacturers to provide an appropriate structure to all related products with the attempt solving the aforementioned problems. Hence, creation of a novel LED structure has become an immediate R&D task and a common goal of the industry.
Considering the defects of the known LED structures, the inventor of the present invention, aiming at creating a novel LED structure that reforms the defects of the existing LED structures and possesses improved practicality, and basing on his years of practical experience and professional knowledge in designing and manufacturing this product, has applied appropriate theories and performing, active researches and innovation. After unceasing researches and repeated retrofit, the inventor herein discloses the present invention that exactly provides practical utility.